Network drivers (bridge, host, overlay, none) in Docker - Step-by-Step Execution

Process Flow - Network drivers (bridge, host, overlay, none)

Start Docker Container

↓

Choose Network Driver

↓

bridge

↓

Create virtual bridge

↓

Connect container

↓

Container runs with chosen network

Docker starts a container and picks one network driver. Each driver sets up networking differently, affecting how the container connects to other containers and the outside world.

Execution Sample

Docker

docker network create mybridge

docker run --net=mybridge alpine ping -c 1 google.com

Creates a bridge network and runs a container using it to ping google.com.

Process Table

Step	Action	Network Driver	Effect	Output/Result
1	Create network 'mybridge'	bridge	Creates a virtual bridge network	Network 'mybridge' created
2	Run container with --net=mybridge	bridge	Container connected to 'mybridge' bridge	Container starts with isolated network
3	Container pings google.com	bridge	Uses bridge network to access internet	1 packet transmitted, 1 received
4	Run container with --net=host	host	Container shares host network stack	Container uses host IP directly
5	Run container with --net=overlay	overlay	Container connected to multi-host overlay network	Container can communicate across hosts
6	Run container with --net=none	none	Container has no network interfaces	Container cannot access network
7	Exit	-	-	All network modes demonstrated

💡 All network driver types have been demonstrated with their effects.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	Final
network_mode	none	bridge	bridge	bridge	host	overlay	none	varies per container
container_network_access	none	isolated bridge	isolated bridge	isolated bridge	host network	multi-host overlay	no network	varies

Key Moments - 3 Insights

Why does a container with --net=host have direct access to the host network?

Because the host driver makes the container share the host's network stack directly, as shown in execution_table step 4, so no network isolation occurs.

What happens if you use --net=none for a container?

The container has no network interfaces and cannot communicate over the network, as shown in execution_table step 6.

How does the overlay network enable communication between containers on different hosts?

The overlay driver creates a virtual network that spans multiple Docker hosts, allowing containers to communicate across hosts, as shown in execution_table step 5.

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the container use the host's network stack directly?

A Step 4

B Step 5

C Step 2

D Step 6

💡 Hint

Check the 'Network Driver' and 'Effect' columns in execution_table row for step 4.

According to variable_tracker, what is the network_mode after step 3?

A none

B bridge

C host

D overlay

💡 Hint

Look at the 'network_mode' row under 'After Step 3' in variable_tracker.

If you want a container completely isolated from any network, which driver should you choose?

A overlay

B host

C none

D bridge

💡 Hint

Refer to execution_table step 6 and the 'Effect' column.

Concept Snapshot

Docker network drivers:
- bridge: default, creates virtual bridge for container isolation
- host: container shares host network stack, no isolation
- overlay: spans multiple hosts for container communication
- none: no network, container isolated
Choose driver with --net option when running containers.

Full Transcript

This visual execution shows how Docker network drivers work. When you start a container, you pick a network driver: bridge, host, overlay, or none. Bridge creates a virtual network bridge isolating containers but allowing internet access. Host shares the host's network stack directly, so the container uses the host IP. Overlay creates a network across multiple Docker hosts for multi-host container communication. None disables networking for the container. The execution table traces creating a bridge network, running containers with different drivers, and their network effects. The variable tracker shows how network_mode and container network access change step by step. Key moments clarify why host shares network, none disables it, and overlay enables multi-host communication. The quiz tests understanding of these steps and effects. This helps beginners see how Docker networking works in practice.

Practice

1. Which Docker network driver allows containers on the same host to communicate using a private internal network?

easy

A. bridge

B. host

C. overlay

D. none

Solution

1. Step 1: Understand the purpose of the bridge driver

   The bridge driver creates a private network internal to the host, allowing containers to communicate securely on the same machine.

2. Step 2: Compare with other drivers

   The host driver uses the host's network directly, overlay connects containers across hosts, and none disables networking.

3. Final Answer:

   bridge -> Option A

4. Quick Check:

   Private internal network = bridge [OK]

Hint: Bridge = private network on one host [OK]

Common Mistakes:

• Confusing host with bridge driver
• Thinking overlay works on single host only
• Assuming none allows communication

2. Which command correctly creates a Docker container using the host network driver?

easy

A. docker run --network=bridge nginx

B. docker run --net=overlay nginx

C. docker run --network=host nginx

D. docker run --network=none nginx

Solution

1. Step 1: Identify the correct syntax for network option

   The correct flag is --network= followed by the driver name, e.g., host.

2. Step 2: Match the driver to the command

   docker run --network=host nginx uses --network=host which is the correct way to assign the host network driver.

3. Final Answer:

   docker run --network=host nginx -> Option C

4. Quick Check:

   Use --network=host for host driver [OK]

Hint: Use --network=host to assign host driver [OK]

Common Mistakes:

• Using --net=overlay instead of --network=overlay
• Confusing bridge and host flags
• Omitting the network flag

3. Given two Docker hosts connected with an overlay network named mynet, what will happen if you run docker network inspect mynet on one host?

medium

A. It shows no containers because overlay networks isolate containers

B. It shows only local bridge network details

C. It returns an error because overlay networks can't be inspected

D. It shows details of the overlay network including connected containers across hosts

Solution

1. Step 1: Understand overlay network scope

   Overlay networks span multiple Docker hosts, connecting containers across them.

2. Step 2: Inspect command behavior

   docker network inspect shows detailed info about the network, including containers connected on all hosts.

3. Final Answer:

   It shows details of the overlay network including connected containers across hosts -> Option D

4. Quick Check:

   Overlay network inspect shows multi-host details [OK]

Hint: Overlay networks span hosts; inspect shows all connected containers [OK]

Common Mistakes:

• Thinking overlay networks can't be inspected
• Assuming inspect shows only local containers
• Confusing overlay with none driver

4. You created a container with --network=none but it still can ping the host. What is the likely cause?

medium

A. The container has another network interface configured manually

B. The none driver allows all network traffic by default

C. Docker daemon is ignoring the network flag

D. The container is running in host network mode

Solution

1. Step 1: Understand the none network driver

   The none driver disables Docker-managed networking, so no automatic network interfaces are created.

2. Step 2: Analyze why container can ping host

   If the container can ping the host, it likely has a manually configured network interface inside the container.

3. Final Answer:

   The container has another network interface configured manually -> Option A

4. Quick Check:

   none disables Docker network; manual config allows connectivity [OK]

Hint: none disables Docker network; manual setup can override [OK]

Common Mistakes:

• Assuming none allows all traffic
• Thinking Docker ignores network flags
• Confusing none with host driver

5. You want to deploy a multi-host Docker Swarm service where containers communicate securely across hosts. Which network driver should you use and why?

hard

A. bridge, because it isolates containers on each host

B. overlay, because it connects containers across multiple hosts securely

C. host, because it uses the host network for better performance

D. none, because it disables networking for security

Solution

1. Step 1: Identify network needs for multi-host communication

   Containers on different hosts need a network driver that spans hosts and provides secure communication.

2. Step 2: Match drivers to requirements

   Bridge works only on one host, host shares host network (not multi-host), none disables networking, overlay connects containers across hosts securely.

3. Final Answer:

   overlay, because it connects containers across multiple hosts securely -> Option B

4. Quick Check:

   Multi-host secure communication = overlay [OK]

Hint: Overlay = multi-host secure network [OK]

Common Mistakes:

• Choosing bridge for multi-host
• Using host driver for container isolation
• Thinking none enables communication